Turbine rotor assemblies typically include at least one row of circumferentially spaced rotor blades. Each rotor blade includes an airfoil that includes a pressure side and a suction side connected together at leading and trailing edges. Each airfoil extends radially outward from a rotor blade platform. Each rotor blade also includes a dovetail that extends radially inward from a shank extending between the platform and the dovetail. The dovetail is used to mount the rotor blade within the rotor assembly to a rotor disk or spool. Known blades are hollow such that an internal cooling cavity is defined at least partially by the airfoil, platform, shank, and dovetail.
Airfoils may be produced in a number of ways. For example, turbine blades may be cast out of nickel superalloy single crystals. In addition, there are general casting methods for producing single crystal structures. Also, turbine blades may be cast with a known crystallographic direction along the casting axis and sometimes even with control of a secondary orientation.